This invention relates to an electronic device having a fuel cell, and more particularly to an information electronic device using a fuel cell of a type which directly oxidizes methanol.
Fuel cells have advantages of high energy efficiency in directly taking electric energy electro-chemically from a fuel, and eco-friendly because fuel cells' emission matter is chiefly water. Therefore, attempts are being made to apply fuel cells to automobiles, distributed power supplies, and information electronic devices. Above all, for information electronic devices, fuel cells are drawing attention as power supplies capable of long-term continuous operation to take the place of lithium batteries, and various kinds of information electronic devices are being devised which are equipped with fuel cells.
For example, there are an information electronic device with a built-in fuel cell made of hydrogen storing alloy (see JP-A-09-213359, p. 3, FIG. 1) and an information electronic device using a methanol fuel cell (see JP-A-2002-49440, p. 3, FIG. 2).
Among methanol fuel cells, a type which takes electricity by direct oxidation of liquid methanol, namely, the so-called Direct Methanol Fuel Cell hereafter referred to as DMFC has an advantage that the fuel cell does not require an auxiliary device, such as a reformer, therefore, the battery system is formed with relative ease compared with fuel cell stacks.
As a fuel for the cathode, oxygen is required, and normally air that includes oxygen is used.
Generally, with fuel cells, the larger cell surface, or, the larger electrode surface provides greater power output. However, because the size of electronic devices imposes a limit to the area of the fuel cell, the fuel cell needs to be formed in a structure that offers greater output while keeping the cubic volume unchanged.